Abstract

The intermolecular potentials for the and systems have been calculated using highly accurate ab initio calculations. The spin-restricted coupled cluster method for the ground state and the multireference singles and doubles configuration interaction method for the excited state , respectively, were used. The potential energy surfaces (PESs) show two linear wells and one that is almost in the perpendicular position. An analytical representation of the PESs has been constructed for the triatomic systems and used to carry out molecular dynamics (MD) simulations of the NO-doped krypton matrix response after excitation of NO. MD results are shown comparatively for three sets of potentials: (1) anisotropicab initio potentials [NO molecule direction fixed during the dynamics and considered as a point (its center of mass)], (2) isotropic ab initio potentials (isotropic part in a Legendre polynomial expansion of the PESs), and (3) fitted Kr–NO potentials to the spectroscopic data. An important finding of this work is that the anisotropic and isotropic ab initio potentials calculated for the Kr–NO triatomic system are not suitable for describing the dynamics of structural relaxation upon Rydberg excitation of a NO impurity in the crystal. However, the isotropic ab initio potential in the ground state almost overlaps the published experimental potential, being almost independent of the angle asymmetry. This fact is also manifested in the radial distribution function around NO. However, in the case of the excited state the isotropic ab initio potential differs from the fitted potentials, which indicates that the Kr–NO interaction in the matrix is quite different because of the presence of the surrounding Kr atoms acting on the NO molecule. MD simulations for isotropic potentials reasonably reproduce the experimental observables for the femtosecond response and the bubble size but do not match spectroscopic results. A general overall view of the results suggests that, when the Kr–NO interaction takes place inside the matrix, potentials are rather symmetric and less repulsive than those for the triatomic system.

Received 03 July 2006Accepted 19 February 2007Published online 06 April 2007

Acknowledgments:

The authors would like to thank their colleagues Maykel L. González-Martínez from Instituto Superior de Technologías y Ciencias Aplicadas in Havana and Luisberis Velazquez-Abad from the University of Pinar del Río for fruitful discussions and suggestions. This work has been supported under Project No. PNCB/2 from Instituto Superior de Technologías y Ciencias Aplicadas and by a Grant-in-aid for The 21st Century COE Program for “Frontiers in Fundamental Chemistry,” and for Scientific Research (KAKENHI) in Priority Area “Molecular Nano Dynamics,” from the Ministry of Education, Culture, Sports, Science and Technology of Japan.